“The more things change…”? Stability of delusional themes across 12 years of presentations to an early intervention service for psychosis

Purpose While the prevalence of delusional themes appears to be consistent across geographic contexts, little is known about the relative prevalence of such themes within a given setting over periods of time. We therefore investigated delusional themes across 12 years of presentation to a catchment-based early intervention service for first episode psychosis (FEP). Methods Systematically collected data from 500 patients at an early intervention service for FEP were analyzed. Four cohorts of 3 years each, from 2006 to 2017, were used to compare the frequency of delusion themes across cohorts. We also integrated into the analysis baseline sociodemographic factors such as gender, age, and highest level of education and clinical factors such as anxiety, depression, suicidality, hallucinations, and primary diagnosis (affective or non-affective psychosis). Results Sex and education level were stable across cohorts, while patient age varied ( p = 0.047). Clinical anxiety, depression, and suicidality at entry were also stable. Across cohorts, the proportion of patients with affective versus non-affective diagnosis differed ( p = 0.050), with no differences in global rating of delusion severity or theme prevalence except for delusions of guilt or sin ( p = 0.001). This single theme difference was not correlated with age or diagnosis. Conclusion Our study suggests relatively stable prevalence of delusion themes across cohorts of individuals experiencing FEP. This demonstrates the potential utility of studying thematic content both for understanding delusions in clinical populations and in research. Future explorations of the relationships between delusion themes and across individual patient episodes should be conducted.